Year Percent 2000-01-01 11.525 2001-01-01 10.175 2002-01-01 10.150 2003-01-01 10.450 2004-01-01 10.575 2005-01-01 10.975 2006-01-01 12.000 2007-01-01 12.500 2008-01-01 12.775 2009-01-01 16.100 2010-01-01 17.575 2011-01-01 18.500 2012-01-01 18.150 2013-01-01 18.125 2014-01-01 14.800 2015-01-01 12.925 2016-01-01 11.075 2017-01-01 10.550